Solar heat collecting system

ABSTRACT

A solar heat collecting system includes a collecting mirror, a receiver, an electrical control unit for controlling the collecting mirror to track the sun, a projection mirror disposed coaxially and integrally with the collecting mirror and the focus of which is coincident with that of the collecting mirror, a through hole disposed at the collecting mirror and the size of which is larger than that of the light spot of the projection mirror and far smaller than the through hole of the collecting mirror, and a reflecting mirror disposed at the side of the collecting mirror opposite to the projection mirror. The receiver is fixedly disposed at the extending direction of the primary optical axis line of the reflecting mirror. A first motor, disposed at the primary optical axis line for driving the whole mirror assembly, is connected to the electrical control unit and runs under control thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2011/072764, with an international filing date of Apr. 14,2011, designating the United States, now pending, which is based onChinese Patent Application No. 201010153222.9, filed Apr. 14, 2010. Thecontents of these specifications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a solar heat collecting device, and inparticular to a low-cost and highly-efficient heat collecting device,which is applicable to fields such as universal civil and industriallarge-scale thermal power generation.

2. Description of the Related Art

A solar heat collector is a device for absorbing sunlight andtransferring the heat generated by the sunlight to a device providedwith heat transfer working substance. The heat collector is a key partconstituting a solar heat utilization system. Different heat collectingmethods form different types of heat collectors, which are generallycategorized into focusing heat collector and non-focusing heatcollector. The efficiency in collecting energy by the non-focusing heatcollector is low and the energy collected by the non-focusing heatcollector is in poor quality. The focusing heat collector is capable ofconcentrating the solar energy collected within a large area to asmaller area or even a spot, thereby obtaining quality andhigh-temperature thermal energy with a concentration ratio of 10⁴. Inpower generation systems of a solar air conditioner, a solar steamturbine, and a solar gas turbine that require medium-high temperaturethermal energy, since the energy flow concentration of sun radiation islow, the non-focusing heat collector cannot reach the requiredtemperature, and only the focusing heat collector is capable of obtainsa high energy flow concentration, and providing a more convenient basisfor utilization of the solar energy.

The focusing heat collector has long been a most effective apparatus forconcentrating sunlight. A focusing reflecting mirror achieves an opticalheat collection effect only by tracking motions of the sun. The focus ofthe focusing reflecting mirror changes with movement of the reflectingmirror. In this way, the size and weight of the receiver for receivingheat are restricted. A large size shades the area of the reflectingmirror's surface for receiving the sunlight, and a heavy weight addsload to the support part and the rotation part. In addition,discreteness, intermittence, and unreliability of the solar energy, andscenarios of cloud and wind, all affect the heat collection effect onthe heat receiving surface of the heat receiver. Moreover, the heatreceiver is in the running state, which hinders output of the receivedsolar energy, especially output and application of high-temperature andquality energy. An optical collector, referred to as heliostat, is beinglong time searched to solve the problem. The heliostat is capable ofconcentrating sunlight only by using a collecting mirror to track themotion of the sun, at a fixed focus.

Since 1930s, many scholars and experts famous home and abroad haveendeavored to design a most effective “heliostat” fixed-focus collectingsystem—tower receiver, whose heat dissipation area is relatively small.Therefore, relative high photothermal conversion efficiency is achieved.The tower solar heat collector is capable of generating hightemperatures reaching 500° C.-600° C., and can conveniently collaboratewith high-temperature and high-pressure thermal power plants. In thisway, a higher thermal efficiency is achieved for solar thermal powergeneration, and collaborative equipment can be simply obtained. However,the cost in constructing such a solar power plant is extremely high, andthe initial investment may be as much as 34-48 thousand yuan per KW.Only the heliostats accounts for 52% of the total costs, and the spaceoccupation exponentially increases with the increase of the power class.The control system for the heliostat is extremely complex. An expert,through years' research, only simplifies M×N control units/mirror into(M+N) control units.

SUMMARY OF THE INVENTION

In view of the above defects in the prior art, the present invention isdirected to providing an FPR solar heat collecting system with high heatcollection efficiency and a fixed receiver.

The objectives of the present invention are achieved through thefollowing technical solutions:

An FPR solar heat collecting system, includes a collecting mirrortracking the sun in real time, a receiver for receiving heat and storingenergy, and an electrical control unit for controlling the collectingmirror to track the sun; where the heliostat solar heat collectingsystem is further provided with a projection mirror that is disposedcoaxially and integrally with the collecting mirror and the focus ofwhich is coincident with that of the collecting mirror, a through holenot interfering with the light spot of the collecting mirror and farsmaller than the surface of the collecting mirror is disposed at thecenter of the collecting mirror; and a reflecting mirror is disposed atthe side of the collecting mirror opposite to the projection mirror, thereflecting mirror, the collecting mirror, and the projection mirror forma mirror assembly, a receiver is fixedly disposed at the extendingdirection of the primary optical axis line of the reflecting mirror, anda first motor is disposed at the primary optical axis line for drivingthe whole mirror assembly to rotate around the primary optical axis ofthe reflecting mirror, where the first motor is connected to theelectrical control unit and runs under control thereof.

Further, in the FPR solar heat collecting system, the mirror assemblyfor heat collection is mounted on a gyro gimbal, and the FPR solar heatcollecting system is also provided with a collecting mirror angleadjusting assembly axially vertical with the rotation axis of the mirrorassembly, including a second motor fraction rod and a clump weight whosetorques are offset relative to the reflection center, where the secondmotor traction rod is connected to the backlight surface of thecollecting mirror.

The reflecting mirror is a plane mirror or a ball mirror with a ringconcave surface.

The lateral surface of the receiver is coated with heat insulatingmaterial.

The shape of the collecting mirror is a paraboloid of revolution havingthe focusing performance, or a convex mirror in a spherical shape.

The first motor and the second motor are selected from the groupconsisting of at least one stepping motor and servo motor.

Further, the FPR solar heat collecting system further includes more thanone mirror assembly, and their respective electrical control unit, wherethe electrical control units are serially or parallelly connected toeach other and run synchronously, and the primary optical axis line ofthe reflecting mirror of the mirror assembly concentrates at thereceiver which has a relatively fixed location.

The application of the FPR solar heat collecting system achieves thefollowing effects:

With a combination of a collecting mirror, a projection mirror, and areflecting mirror, and use of optical principles such as opticalfocusing, projection, and reflecting, radiation from the sun orcelestial bodies is constantly reflected to a fixed receiver or ocular.This effectively improves the concentration ratio of the sun to over 100thousand times, thereby bringing convenience for utilizinghigh-temperature solar energy. Meanwhile, the system is simple instructure, and imposes a relatively low requirement regardingcombination with the buildings, and is less-costly. To be specific, thesystem costs less than nuclear power, and causes no hazards. During useof the system, the solar energy in all wave bands is absorbed, and theheat conversion efficiency is high.

The following further describes the specific embodiments of the presentinvention with reference to the drawings, so that the technicalsolutions of the present invention are better understood.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of an FPR solar heat collectingsystem according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of running state according to theembodiment illustrated in FIG. 1;

FIG. 3 is a schematic principle diagram of an optical path of the FPRsolar heat collecting system according to an embodiment of the presentinvention;

FIG. 4 is a schematic structural diagram according to another embodimentof the present invention (the drawing of a projection mirror isomitted); and

FIGS. 5 a and 5 b are elevation diagrams of two preferred structureforms of a collecting mirror according to the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Various embodiments of the present invention provide a system and methodfor positioning using an active RFID tag. The following sectiondescribes the technical solution of the present invention in combinationwith accompanying drawings and embodiments.

To further improve the energy conversion efficiency of theenvironmental-friendly and inexhaustible solar energy and promoteapplication of the solar energy in various energy-consuming fields, thepresent invention provides a solar heat collecting system. The presentinvention breaks through the prior art—the inherited idea of a heliostattower heat collecting system, and has innovatively enabled the sunlightto constantly radiate towards a fixed receiver by using opticalprinciples such as optical focusing, projection, and reflecting.Therefore, no matter how the collecting mirror rotates, the primary axisstill does not change. The heat collecting system described herein istemporarily referred to as “FPR”.

FIGS. 1 to 3 are respectively a schematic structural diagram, aschematic diagram of running state, and a schematic principle diagram ofthe optical path according to a preferred embodiment of the presentinvention. As shown in the FIGS, a projection mirror 2, which isopposite to the projection surface and the focus of which is coincidentwith the collecting mirror, is disposed on the other side of the focusof the collecting mirror 1. The collecting mirror 1 and the projectionmirror 2 are integrally connected through a gyro gimbal 4. A throughhole 11 is disposed at the part, which is spotted by a projection lightspot, at the bottom of collecting mirror 1. A reflecting mirror 5 isdisposed below the through hole 11, and is connected to the gyro gimbal4 and a hole border. The reflecting mirror 5 is capable of rotating onthe gyro gimbal. The reflecting mirror, the collecting mirror, and theprojection mirror form a mirror assembly. A receiver 3 is fixedlydisposed at the extending direction of the primary optical axis line ofthe reflecting mirror, and a first motor is disposed at the primaryoptical axis line for driving the whole mirror assembly to rotate aroundthe center of the reflecting mirror, where the first motor is connectedto the electrical control unit and runs under control thereof.

The above technical solution may be optimized as follows: The FPR solarheat collecting system is further provided with a collecting mirrorangle adjusting assembly axially vertical with the rotation axis of themirror assembly, including a second motor traction rod 61 and a clumpweight 62 whose torques are offset relative to the reflection center,where the second motor traction rod 61 is connected to the backlightsurface of the collecting mirror. The first motor and the second motormay be selected from the group consisting of a stepping motor, a servomotor, or other similar precision control motor.

The reflecting mirror is a plane mirror or a ball mirror with a ringconcave surface. The shape of the collecting mirror is a paraboloid ofrevolution having the focusing performance, or a convex mirror in aspherical shape. In addition, the lateral surface of the receiver mayalso be coated with heat insulating material or be thermally-insulatedusing vacuum heat insulating technology.

The reflecting light at the center of the reflecting mirror is referredto as the primary optical axis. The first motor disposed on the primaryoptical axis line enables the mirror assembly of the entire heatcollecting system to rotate around the primary optical axis, trackingrise and fall of the run and moving synchronously with the sun. Withadjustment of the elevation angles in the south and north direction, thesystem ensures that the sunlight vertically radiates to the collectingmirror. Since the entire collecting mirror system rotates around theprimary optical axis starting from S as an originating point. Theincident light from the reflecting mirror forms a constant angle withthe primary optical axis, and the incident beam (projection beam)constantly radiates, along the direction of the primary optical axis, tothe receiver through reflection.

The sun rises in the east and falls in the west, and moves between theTropical of Capricorn and the Tropic of Cancer, changing at a totalangle of 470 degrees, with 0.2575340 degree each day. To ensure that thefocusing system is constantly vertical with the sunlight and achieves anoptimal heat collection effect, a second motor is mounted at the axiswhere S point is vertical with the paper surface, to enable the entirecollecting mirror system to rotate left and right around S axis, andadjust the inclination angle of the collecting mirror to ensure that thecollecting mirror is vertical with the incident sunlight. To ensure thatthe reflecting light does not change along the primary optical axis, theinclination angle between the reflecting mirror and the horizontaldirection is adjusted to ensure that the incident angle is equal to thereflection angle.

During adjustment of the inclination angle of the collecting mirror byusing the motor, the elevation angle of the reflecting mirror issimultaneously adjusted. This, specifically, ensures that a fixedheat-receiving object (a target or ocular) constantly and effectivelyreceives the sunlight, satisfying the requirement of an FPR.

To make the reflection light to form a light spot at the heat collectoror the FPR, the reflecting mirror is made to a ball and ring-shapeconcave mirror with a ball, similar to a tyre, that is, the projectionlight focuses at one point through secondary focusing. The FPR systemwith the above single-mirror assembly is a universal daily necessitysuch as the solar air conditioner, and solar shower. The diameter of thecollecting mirror does not need to be made larger, and in addition, thesystem does not need to be disposed on the roof to receive sunlight. Tobe specific, the system satisfies basic needs in the daily life at alower generation power consumption ratio (smaller than 0.1%).

Besides, the FPR heat collecting system according to the presentinvention sees a wider application in solar thermal power generation. Tobe specific, the heat collecting system includes more than one mirrorassembly and their respective electrical control unit. The electricalcontrol units are serially or parallelly connected to each other and runsynchronously, and the primary optical axis line of the reflectingmirror of the mirror assembly concentrates at the receiver which has arelatively fixed location. Compared with the currently popular heliostatsystem, the FPR solar heat collecting system has a notable power costsper unit. In addition, in aspects of space occupation, and solar energyconversion and utilization rates, the system according to the presentinvention is advantageous.

Therefore, according to the technical solutions of the FPR solar heatcollecting system, with a combination of a collecting mirror, aprojection mirror, and a reflecting mirror, and use of opticalprinciples such as optical focusing, projection, and reflecting,radiation from the sun or celestial bodies is constantly reflected to afixed receiver or ocular. This effectively improves the concentrationratio of the sun to over 100 thousand times, thereby bringingconvenience for utilizing high-temperature solar energy. Meanwhile, thesystem is simple in structure, and imposes a relatively low requirementregarding combination with the buildings, and gains high heat conversionefficiency. In the case of a project with an equivalent scale, thesystem costs less than nuclear power, and causes no hazards. Suchcharacteristics facilitate promotion and popularity of the solar energyresources in fields such as the civil and scaled thermal powergeneration and solar air conditioning.

1. An FPR solar heat collecting system, comprising a collecting mirrortracking the sun in real time, a receiver for receiving heat and storingenergy, and an electrical control unit for controlling the collectingmirror to track the sun; wherein the heliostat solar heat collectingsystem is further provided with a projection mirror that is disposedcoaxially and integrally with the collecting mirror and the focus ofwhich is coincident with that of the collecting mirror, a through holenot interfering with the light spot of the collecting mirror and farsmaller than the surface of the collecting mirror is disposed at thecenter of the collecting mirror; and a reflecting mirror is disposed atthe side of the collecting mirror opposite to the projection mirror, thereflecting mirror, the collecting mirror, and the projection mirror forma mirror assembly, a receiver is fixedly disposed at the extendingdirection of the primary optical axis line of the reflecting mirror, anda first motor is disposed at the primary optical axis line for drivingthe whole mirror assembly to rotate around the center of the reflectingmirror, wherein the first motor is connected to the electrical controlunit and runs under control thereof.
 2. The FPR solar heat collectingsystem according to claim 1, wherein the mirror assembly for heatcollection is mounted on a gyro gimbal, and the heliostat solar heatcollecting system is further provided with a collecting mirror angleadjusting assembly axially vertical with the rotation axis of the mirrorassembly, comprising a second motor traction rod and a clump weightwhose torques are offset relative to the reflection center, wherein thesecond motor traction rod is connected to the backlight surface of thecollecting mirror.
 3. The FPR solar heat collecting system according toclaim 1, wherein the reflecting mirror is a plane mirror.
 4. The FPRsolar heat collecting system according to claim 1, wherein thereflecting mirror is a ball mirror with a ring concave surface.
 5. TheFPR solar heat collecting system according to claim 1, wherein thelateral surface of the receiver is coated with heat insulating material.6. The FPR solar heat collecting system according to claim 1, whereinthe shape of the collecting mirror is a paraboloid of revolution havingthe focusing performance, or a convex mirror in a spherical shape. 7.The FPR solar heat collecting system according to claim 1, wherein thefirst motor and the second motor are selected from the group consistingof at least one stepping motor and servo motor.
 8. The FPR solar heatcollecting system according to claim 1, comprising more than one mirrorassembly, and their respective electrical control unit; wherein theelectrical control units are serially or parallelly connected to eachother and run synchronously, and the primary optical axis line of thereflecting mirror of the mirror assembly concentrates at the receiverwhich has a relatively fixed location.